Thanks for posting me a link to this thread.
I particularly like the 'hood' over the cooktop.
I'm thinking this could be adapted to become a bottom heated oven, but I have a long way to go before I can try it!
Thanks for that info., I'd often wondered if that was the case, but as I only use well dried, smaller diameter stuff I've never really bothered/needed to try. I don't use so much that storage is an issue, so I always have dry stuff available.
Mark Deichmann wrote:It takes ash about 15 -20 years to reach a diameter of 4 inches at chest height. Keeping in mind that where you cut one tree you get 3-6 on average back. Its long term at best but a nice tree to manage and nice to look at too.
Depends on climate and growing conditions, also on age of tree/rootstock. Round here, it grows a lot faster than that, more like 10 years to 4" diameter, though personally I wouldn't want it to get that thick, especially for the first cut. Not only will it be a shock to the tree, but it's more work to cut and handle generally. Coppicing (or pollarding) is the way to go. An established rootstock cut down regularly will put on much more growth than a new sapling. Typical cycle times are given as 7-10 years, but it really depends on how many stems you leave, and how thick you want them.
I have one that was cut at waist height (long story) when it was about 3" at that height, about 10 years ago, it now has three main stems all 4" or slightly more at chest height, but then again, I know where there are some ash trees in a car park that have hardly grown at all in the last 12 years.
For BTU per acre per year SRC willow is the best, and can be burnt in a rocket stove/heater, but if you need logs, I reckon ash cut at 2-3" is the best. Cutting down on your energy requirements will make 'which wood is best to grow for burning' less of a concern and you can have more space for growing other things, even other trees with other uses. Rockets aren't fussy about what they burn and will burn sticks, so once you have one you really don't have to grow anything special for fuel, just enough to provide adequate quantities of prunings.
To make stoneware pottery, you need stoneware clay. You could possibly use that clay to make a kiln to fire pots made of the same clay, but stoneware is vitrified clay, and that is a different ball game from earthenware.
On the positive side of things, I know from experience that you can use local earthenware clay to make a kiln to fire pots made of the same clay, and it will last many, many firings.
Unless you are seriously into medieval reenactment I recommend a domed downdraft style. Superficially this is much like the kiln in the video, but has a single central hole for the fire to enter the kiln and typically four equally spaced exit flues. Once the fire is going nicely the central hole in the top should be completely blocked so the hot gases redirect to the exit flues. (think rmh barrel, only without the insulated riser and with flues to encourage the draft rather than a bench.)
You'd still need a bit of metal for the door, but there's none in the stove itself, and the bench is different type too, with no flue pipe.
Thanks for posting, but actually yes. It's not just having a door that put me off it though. Among other things more personal to me, I don't see how he can call it a rocket stove when it doesn't have a riser, and in the video he actually titles it a masonry heater . . .
Looking on the positive side though, it does seem to be exhausting satisfactorily through a bench even without a riser!!
Posting on here seems to do wonders for my search results, at least, for a little while. . . I've actually found a couple of diagrams and pictures of almost exactly what I am thinking of making, and afaict they work alright!
Hi Thomas, to cut a long story short, between my finances and ministry of sadness wranglings, for metal, I am limited to what I have had lying around for years, and that's not much!
I do keep my eyes and ears open for anyone who might be interested in these sort of things, but due to the normal (i.e. not like me ;P ) demographic of the area I live in, the closest I have found was over an hour away, and they had to remove it or be unable to insure a very expensive (and wooden) building . . .
Metal barrels are as rare as hens' teeth around here and flue pipe is prohibitively expensive too, so I pretty much need to avoid metal but I would really like to make an rmh.
I know a rocket stove is doable without metal, but a lot of heat is wasted, which I would like to 'capture' in a cob bench/sleeping platform. I am concerned that without the rapid loss of heat provided by a large exposed metal surface, there will not be sufficient force in the draught to force the exhaust through any significant lenght of horizontal flue, especially once the downward section has warmed up.
The only examples I have been able to find of anything without metal are just stoves, and only one of them a proper rocket even. The best of them is Glenn Herbert's, and that exhausts into a vertical flue, after only a tiny downward section.
Being unable to find anything like what I am hoping will work, makes me very wary of the massive amount of work involved in making a cob bench in the first place. . .
If anyone has made one, or has seen one that works or has a link to one, I would love to hear about it.
Healthy newly hatched chicks will have a reserve of yolk inside them, as well as being well hydrated. They also slep a lot for the first few days, but even if the chicks don't need water, the hen does!
The cheeping of the chicks will keep the hen's attention more than eggs. While it's true that some hens are better at doing things naturally than others, I have only once seen a broody prefer eggs to chicks, and that was because only one hatched.
Sometimes chicks can hatch days apart, even after the hen has mostly left the nest and taken the chicks to water etc. A bit of cooling now and then is more normal than the constant even heat of an incubator.
When you say three 'stillborn' do you mean out of the shell? That is very odd for several reasons, including some you won't want to hear about!
Basically what I would call 1 in 2 slope is typically referrred to as 6:12 on here, and there are plenty of references to green rooves with that slope, so I presume it works well.
As for how much 'growing medium' is needed,the only specific thread I can remember was something like " 50 year old roof", but I can't find it any more.
That roof had nothing put on top, but nature had deposited a lot of pine needles, or maybe that was the one that was covered with moss . . . anyways, I've seen from that (nothing) to two feet of soil and everything in between recommended, and considering that it's so dry this year that even stuff in the ground is dying, there is no point putting anything on top more than is needed for protecting the EPDM and for insulation, so I have completely changed my plan and will be going for a couple of inches of sand or pebbles (if I can find suitable smooth ones) on a virtually flat roof.
What ever will survive up there will eventually find its own way there. I'll still try some stuff, (sedums and grasses, but at the end of the day it's whatever nature permits.
Joel Hollingsworth wrote:
Sorry if this is a stupid question, but do you suppose water is condensing in the exhaust pipes? Have you provided for removing that water?
General comments on rocket heaters:
Water does condense in the pipes on other RMH systems, but not to the point where it would pool and do damage. Earthen masonry is pretty forgiving up to moisture levels around 13-15%, and cob both absorbs and evaporates water readily.
My gut is that any condensed water gets evaporated out again once the fire dies down. Some amount of cooler, drier air flows through the warm pipes as the fuel load diminishes, especially if you aren't tending the fire super-closely and let it burn out completely before shutting the burn door.
The time when RMH's tend to be really drippy is just after building them, especially if you build it in the fall when the weather is cold and wet. Water comes out everywhere - the cob faces, the pipes, the drainage underneath.
We do try to orient the cleanouts so that water can drain down and out.
Ahh just the question and answer I have been looking for!
Also, thanks to the bit in blue, I have just realised something else that helps keep the exhaust tubes dry . . .
While the rocket is going full blast, carbon, hydrocarbons and hydrogen are all burnt at full tilt but the hydrogen and hydrocarbons, are actually driven off and burnt first being volatile, so when it (or any wood fire) dies down there is a quantity of charcoal still to be burnt, so the last 'combustive activity' is actually dry, so the 'dying breath' of the fire (provided you let the charcoal burn before you stop off the air inlet) is actually to flush the tubes with hot dry exhaust.
I cant find a forum for rooves, so I've plumped for the natural building forum . . .
I keep finding loads of stuff saying 1-2% slope, but that's so low that it's actually called flat roofing when it's not got stuff growing on it. I've seen sedum planted rooves around here that have a distinctly noticeable slope to them though, and then there's pictures on the web of traditional sod roofed houses which are very steep, but are made with birch bark or somesuch as the waterproof layer which I'm pretty sure provides more resistance to slipping than EPDM. I don't need my roof to be that steep (and I don't have any birch bark or equivalent either anyway), but a slope of about 1 in 2 would be really good for my particular project.
Is such a slope (1 in 2) practical with EPDM as the waterproof layer? (Or roofing felt as a possible alternative.) I am thinking of overlaying it with sand/gravel 'ballast' topped off with significantly sand enriched topsoil, and then either turf or maybe a thin layer of unadulterated topsoil and seeds or plug plants. (Our topsoil is so clay rich that it cracks after a few dry days in summer - not good for a roof without a waterproof layer, but maybe ok with one?)
Ok, you convinced me! I'll give it a go. I've got three and a half weeks before I'll really need it. (For a new cob oven 'christening' party.) We'll probably be using spelt, so I'll try some of each (separately). Spelt, wholemeal, and multigrain. I've got plenty of old kilner jars.
Roberta Wilkinson wrote:If you leave it too long without use, it will get a brownish/blackish liquid on top that doesn't taste or smell great. If it's just a tiny bit, you can stir it back in, but I preferred to pour it off and add back an equivalent amount of fresh water. If you let it go too too long, your yeast will die and you'll need to start over.
That reminds me of MIL peering at the starter and debating with someone (one of her SIL's), whether it was still viable or not. Home bread baking was getting rarer and rarer, even though, ironically, people were also getting more appreciative of home baked bread. Making starter from scratch was already a lost art, at least in our small town.
Chlorinated water, not a problem, I use cooled boiled water when baking bread anyway.
Well, if you can make 'proper' sourdough starter from just water and (wholemeal?) flour, will it be so terrible to help things along with a bit of bakery yeast?
I know that when making ginger beer, there is a bacteria that feeds on the alcohol, thereby keeping the yeast alive for longer making the end product fizzier. Hmm, a bit of googling reveals that lactobacillus can help keep down other moulds. It just so happens I have some yoghourt in the fridge (I eat tons of it) . . .
The more I read the more I get confused.
My MIL was in charge of the sourdough, but apart from it being kept in a glazed earthenware jar, in a cool dark place, and added to the new dough mix, I have no idea what she did with it. I'm pretty sure that once it was in storage, nothing was done to it, until it was needed again, because one time, it had been longer than usual between uses, and MIL couldn't revive it, so had to get some from neighbours instead.
So, so far my plan is to make some bread, with multigrain flour, and fresh yeast, and keep some back, in a jar in a cool dark place with a saucer on top to keep the wildlife out. . .
I figure MIL probably didn't add more flour, as only a fraction of the starch will have been consumed to make the bread rise, so there's plenty left for the yeast to feed on for a couple of weeks at least. I figure she probably didn't add sugar either, for the same reason.
I guess I'll actually try a couple of variations, one 'as is' and one with added water, as I seem to remember it was quite sloppy at some point.
Any ideas what my chances of success might be? 0.o
Very nice! One thing puzzles me though. If backer board and tiles are sufficient protection for the framing of the raised hearth, why not just remove the floorboards in the area and replace with backer board and tiles?
You're wanting to build a cooking oven with them right? They'll stand those temperatures easily but the cob between them will shrink but the tiles won't, which might cause problems.
I think the 'need' for support while building arches is grossly exaggerated in the 'west'. There are thousands of domes and arches in the middle east that were made without support, and some of them are huge. For some reason western builders don't believe that they were built without support and insist that everything be supported. Which is probably not a bad thing for 'health and safety' on large structures, but small stuff really doesn't need it, especially when using cob. Any half taught pottery student can build a pretty decent coil pot with normal clay, and cob is even easier to build with.
I've managed to find a couple of videos that show the possibilities:
These are amazing and a lot thinner than I've seen 'irl'. If you do try building this way, be aware that each layer has dried and stiffened a bit before the next layer is added. (just a bit, nowhere near completely dry, still soft enough to blend with the next layer)
This one uses cob and is completely different from what I was expecting, but still gives a lot of ideas.
The one I saw being made was a lot bigger and made like a coil pot, the finished item being a cross between the two types, and set into the ground rather than a barrel.
Friends have recently built an oven using sand as a former, and had problems with cracks. I strongly suspect that this was due to the sand former preventing the clay from shrinking normally, like a pot would!
I lived in a cob house for about ten years. night time winter temperatures were typically below -30C, with lots of snow.
Dealing with the snow? We had flat roofs, so after a snow fall, before going to work, the snow had to be pushed off.
Heating? We only had korsi/kotatsu, very cosy, sometimes indirectly supplemented by a cooking stove. Possibly not as green as rocket heaters, but then again it might be greener, as we weren't heating space.
eta the (traditional design) cob house was much more comfortable in both summer and winter than newer brick/concrete buildings.
No, sorry not done yet. I will post pictures when I get round to it, but I've been distracted by greenwood projects initiated by the felling of a large ash tree. I also need to purloin sufficient clay from the excavations, and it's heavy stuff with no easy wheelbarrow route, so has to be carried several yards.
On the plus side, I have been on the day classes on cob/daub/clay lump, and am a lot more comfortable about trying it out with the local stuff and whatever else I can get easily/free.
Who said anything about burning trees? Perhaps I should mention that my interest in rocket stoves etc. comes from years of bonfires, of all the twiggy stuff that just isn't practical to burn indoors, that still has to be got rid of and would take way too long to compost. Right now I have four big heaps of twiggy stuff, and that's just from last year and not counting the logs still in store, or the ash tree that is mainly going for craft projects.
If I can use some of the mountains of stuff that goes up in smoke every year from my garden to heat a bath or cook something on, so much the better. I certainly won't be burning decent logs for it! Although, tbh, as I can't fit a RMH in my house, it probably would be more efficient to use the logs for the rocket bath than put them on the open fire to heat the back boiler!
Trust me, if indoors was an option, it'd be indoors!!
That's what I was thinking originally. The link shows an improvement on that, and is the type I will be trying. (Actually the same one as Julia linked to earlier in the thread. )
I don't see any point in complicated plumbing and gizmos for really hot water; A bath doesn't want really hot water, just warm bath temperature water to soak and wash in, not turn the occupant into cannibal stew.
Rose, I think there is possibly some point to a cob thermal mass in addition to the water. I think it may help keep the water warmer for longer. (More mass -> more heat stored -> longer time to cool down.) ?
Sue, I think the inverted bell system is more suited to 'indoor' heating, as a lot of heat is given out from the bell. This (the one in the link above) is just a basic insulative cob rocket stove with added mass, or to put it another way, a basic bush bath made more efficient by the use of an insulated chimney and firebox.
Thanks both. There's a lot of useful info there. Some of those calculators look promising, too.
I could do with a better drawing program, 'Paint' is the best I have.
I've got to the stage where I need detailed drawings, so I'll do them nicely by hand and scan them in when I'm done.
I think my favourite builders' merchants have more chunky timber than is in their catalogue, so I'll check with them first, otherwise, 8ft long 4x8's are the easiest to get hold of.
IDK why I was thinking of the rafters running longwise. 16ft rafters (4.8m actually) work out just right for the deepest section, supported 2ft in from each end. Unless it works out too much more than 2x8's at 24", I'll use 2x7's at 16". I don't trust 19mm OSB not to sag with 24" span, and I might even go with 2x8's at 16", the extra support will give me the option of a little light 'greening' later.
Sadly, at this stage, there isn't anything particularly permaculture about the workshop I am planning, except that I intend it to last a very long time! Once the roof is up, I can choose/experiment with solid cob, wattle and daub and rendered straw bales. I have made a 'freestyle' strawbale shed, and it's ease of construction makes strawbale very tempting, but I would like to make use of passive solar heating and I gather that solid cob is best for that, but then again, not much sun is going to hit the back wall if any ... but I digress, the current decision to be made is about supporting the roof:-
I am trying to figure out what size timbers I need for it's basic frame. It will only be small by US standards, 30m2 max due to local regs (UK). Regs also make building above 2.5 m high, prohibitively expensive so a proper timber frame is not really needed. It's got to be flat roofed. Sadly there is no source of round timber within sensible distance, so it's got to be standard flat roof construction, with rafters and EDPM. On the plus side, I can find no end of tables with detailed info on rafter spacing, span, loading etc. So the actual roof is fairly straight forward, it's just 'how to support it' that's the problem.
It seems anything goes on top of what folks in the US call stick framing, but I would rather not have too many uprights to work around and at 7m longest measurement, I am going to need some sort of support in the middle, where I really want open space. I am thinking some arrangement of posts and beams, but I can't find any usable info on dimensions thicknesses etc. Can anyone point me in the right direction, please?
Is 'Outdoor Structures' Time Life any good or is it only fences, pergolas and deck type things?
Eivind Bjoerkavaag wrote:I haven't experience with it but it sounds like an awesome plant if it can be controlled. The caretaker of True Nature Farm, the guy from Paul Wheaton dandelion video, said bindweed really improves the soil.
It can't realy be controlled, that's the problem. Turn your back on it and it will drag your plants down and bury them. It has no merits that can't be got from other less aggressive plants.
Pete Hwan wrote:Marion, can you explain more regarding:
"With patience and regular persistance, bindweed is relatively easy to get rid of, as it doesn't spread sideways like the cooch grass or ground elder."
Tell me more about the not spreading sideways part. I'm trying to discern the critical insight here. From what I can tell, our bindweed spreads quite aggressively via underground roots.
Hmm, maybe a different variety/species from the stuff around here. Or possibly a misunderstanding due to my trying to keep things short and simple.
Digging down to remove roots, I find they are always pretty much vertical, lots of wiggles and 1" diameter spirals, but all basically vertical.
It will spread sideways, but only above ground, where you can see it, like ivy. You don't have to dig to stop it, but you do have to be regular in your attention to the areas where you want to eradicate it.
Cooch Grass and ground elder by contrast have very stongly horizontal spreading roots. If your bindweed doesn't have horizontal roots like that, then I suggest that you simply have a lot of remnants over a large area. Just because you have gotten out all that you can get down to, won't stop it coming back from some deeply buried root possibly over a year later. You do have to be on your guard and persistant.
Jessica Padgham wrote:When I was reading up on growing buckwheat I came across a claim that it inhibited bindweed. I haven't tested this thoroughly but the area that I planted with buckwheat does seem to have less of the bindweed than the surrounding area. Another tip I read here on Permies, and I think it was from Matu Collins, was instead of pulling the plant to curl it up and cover it. I think she read somewhere that the pulling actually stimulates it to grow even more. Again, I haven't been thorough but I am gaining ground in my strawberry bed with this method.
It certainly helps make it bring it's roots to the surface. It's important not to let it get to the light though.
My Mum and I have developed a philosophy for eradicating noxious weeds. Find a use for it and it attempt to use/cultivate it for that purpose, and sure as eggs are eggs it will up and dissappear! My Mum's original input to the pholosophy, was from wartime, when her father discovered that if you placed a saucer over a dandelion plant, it would blanch and be edible like endive. I don't know if they ever got any to eat, but they soon ended up with a dandelion free lawn!
In more recent times I have discovered that dandelions make good chicken food as does goose grass, chickweed, and fat hen. I used to have lots of all of them, now I have just a little goosegrass. I am even contemplating buyng dandelion and fat hen seed!
Bindweed, ground elder and cooch grass all IIRC are good mineral collectors, so make good (if stinky!) liquid feed for other plants.
With patience and regular persistance, bindweed is relatively easy to get rid of, as it doesn't spread sideways like the cooch grass or ground elder. If you have heavy clay that will benefit from digging you can speed the process a bit by chasing the roots down as far as you can go. Be careful you don't break into hell though!!
I have a standard sized bath that will do nicely. It's been lurking in the hedge for years, well, it didn't start out in the hedge, it kind of grew into it. I stashed it there years ago, hoping to make a grey water reed bed system with it. Now, clearing that part of the garden for other reasons, it's come to the surface again, and in the interval between it disapearing and reappearing, I've heard about bush baths and love the idea, and seeing as it's cast iron (hard to come by nowadays) and pretty much anything will do for greywater, it would be wasted for greywater. (I have at least two small (attic) water tanks not doing much which would do nicely. )
Satamax, In what way wasteful? Also, I don't see the use for a bell for heating a bath, it's either heat wasted before it even gets to the bath, or an unnecessary complication after. Please explain what it's for.
hehe That's what I thought might have to be the case when I starteded this thread, but Julia's link https://rocketstovestuff.wordpress.com/about/ covers all the bases, simple construction, basic materials, no cooling the fire/loss of efficiency, and with the added bonus of no hotspot to worry about.
There is one thing I think might be a bit dubious about it, and that's the length of horizontal before the chimney, but I'm guessing if it's slow drawing, a bit more height would solve the problem (?) and a few embers dropped down the chimney at the start would help get it going too.
Love that cob hot tub, Julia! I had been about to shelve the idea permanently, but the simplicity of that one has put it back on my list of projects, as a separate project.
Love Dale's rocky rocket stove too. (I had already bookmarked the thread of it's build. )
Steve Harvey wrote:Those are cool designs, I like the more realistic one. Like the picture with the tub on the burn tunnel I would incorporate the tub as part of the thermal mass, and surround it in cob.
Yes, I think the tub would be better placed as a heat mass rather than directly over the fire too. I'm hoping someone on here has actually tried it and can report back.
In particular, I'm wondering about water condensing issues, as a tub of water is going to keep the mass below cooler than a dry bench would.
I've seen quite a lot of stuff with complicated gizmos and lots of tubing, seemingly intended to get near boiling water out of a tap, and a lot of them seem to be doomed to failure as they are trying to use the hottest part of the fire, ignoring the fact that the presence of non pressurised water in that region is going to take so much heat out of the combustion that it's going to seriously reduce efficiency.